ABSTRACT BACKGROUND: Type 2 diabetes mellitus (T2DM) is the most expensive chronic disease in the U.S. Lifestyle modification is central to T2DM management, but long-term adherence to dietary recommendations is difficult. A key challenge is the difficulty of coping with cravings for high carbohydrate or sugar-laden foods in an environment where these foods are tempting and widely available. One mechanism by which mindfulness may increase long-term dietary adherence is by better equipping individuals with skills to experience food cravings and difficult emotions without eating in response. Such approaches seek to strengthen abilities to be non- judgmentally aware of, tolerate, and respond skillfully to food cravings and difficult emotions without reacting impulsively or maladaptively. We hypothesize that improved ability to manage food cravings and emotional eating is a key mechanism through which mindfulness-enhancements can improve dietary adherence. We will test mindfulness-based intervention (MBI) components for improving dietary adherence based on our group?s recent NCCIH-funded trial testing MBI components for obesity, which showed evidence of improved fasting glucose, lipids, and potentially weight. Although the particular diet employed is not the focus of this study, we plan to use a diet with about 10% of calories from carbohydrate as: (1) it induces a low level of ketone production, which we will use as a biomarker for dietary adherence; (2) prior studies suggest it improves metabolic parameters in T2DM, including glycemic control. METHODS: We will use ecological momentary assessment (EMA) methods to measure eating in response to difficult emotions and/or food cravings. In the R61 phase, we will ensure this measure is appropriate for further testing and assess the impact of the MBI components on our hypothesized behavioral mechanisms in N=45 persons with T2DM. We plan 3 waves of 15 persons each with 12 weekly sessions. All participants will attend an in-person group course providing education on basic behavioral strategies for diet and physical activity. Participants will be randomized to receive this education alone (Ed) or this same material with added MBI components (Ed+MBI). We will also pilot test two levels of intensity of maintenance phase intervention (monthly group meetings alone or supplemented by individualized attention) to prepare them for R33 testing. We plan an R33 phase trial in which 120 persons with T2DM will be randomized (using a 1:2 ratio) to Ed or Ed+MBI conditions and followed for 12 months, including a 9-month maintenance phase. We will test the effects of MBI components on our proposed behavioral mechanisms and dietary adherence, and obtain preliminary data on MBI component effects on weight and glycemic control. We will use an innovative adaptive intervention design to optimize maintenance phase intensity, which we believe may be key to augment the MBI effects. SIGNIFICANCE: Our studies promise to extend our understanding of how MBI components can improve dietary adherence and have broader implications for understanding the mechanisms of MBIs for other conditions such as addiction.